What is the correct (or good enough) "exposure" for an interior render?

Lets say I"m using Nishita sky set to strength of one and the sun positioned at high noon.

My room has an open door and 2 open windows on the north side (y+) and 2 open windows on the west side (x-). What exposure would you use for your renders if we assume the Nashita sky light is real world accurate for a bright sunny day with no clouds?

image

Pretty simple. Drop it down until it looks good. If the room have dark materials you’d probably have to live with overexposed sunshine to get the room itself bright enough, but it the room had very bright materials you could lower the exposure further while having the room itself bright enough.

I usually don’t care if sun causes overexposed hotspots, it’s kinda part of the game unless you want to even it out with internal lights/flash and so on. In this case, probably between -4 to -2, or adjust the sun to be bigger and weaker to simulate some clouds.

Use false color to check exposure, magenta means underexposed, orange/red overexposed, you need to avoid both, unless is intented. A good one will keep your scene between light blue and yellow, 18% gray is the proper color. Here you find more information about this gray value. If you’re looking for physical accuracy, Maxwell Render is an engine built for that but in most cases an artistic aprouch will solve. Also, use Filmic or Tonemap node in compositor to adjust your render. Filmic will give better photography results.

Original:

Original False Color:

Tonemaped:

Tonemaped False Color:

Background isn’t white. It was sampled from a overexposure pixel.